The present invention relates to an arrangement for adjusting the inclination of the backrest component relative to a seat component of a seat in general, and more particularly to an arrangement of this type which is especially suited for use in vehicle seats.
Various constructions of hinges which tiltably mount the backrest component on the seat component of a vehicle seat are already known and in widespread use. Among these, there are such in which the hinge members of the hinge which are stationarily connected to the components of the seat are mounted on one another for relative tilting about a pivot axis, and each of them is provided with an internal annulus of teeth each of which has a different number of teeth but both of which may have the same diameter. Then, it is also known to provide an adjusting member which causes the hinge members to conduct relative tilting adjustment movement and which meshes with the teeth of the internal gear annuli of the hinge members.
One arrangement of this type has been disclosed in the German Patent DT-PS 1,291,570, in which an internal gear annulus is associated with each of the hinge members, the two gear annuli having different numbers of teeth and also different diameters. Then, an external spur gear meshes with the internal gear annuli, the diameters of the spur gears being different, but the numbers of teeth being the same. These spur gears are arranged on an eccentric section of an adjusting shaft. When the adjusting shaft rotates, the region of meshing engagement of the teeth of the internal gear annuli and of the external spur gears revolves or orbits in correspondence to the position of the eccentric section. Owing to the differences between the numbers of teeth of the two internal gear annuli, there is obtained a relative movement between the hinge members which is usable for the adjustment of the inclination of the backrest component of the seat.
Another arrangement of this type is known from the German Patent DT-Gmb 6,604,918, wherein again an internal gear annulus is associated with each of the hinge members. The internal gear annuli have different numbers of teeth, but the teeth of the internal gear annuli are located along a diameter which is the same for both of the internal gear annuli. Then, a tilting axle which is provided with a handle is connected for joint rotation with an arm on which a support axle is mounted in parallelism with the axis of the tilting shaft and at a distance therefrom. A satellite gear which meshes with the internal gear annuli is rotatably supported on the support axle. When the handle is rotated, the satellite gear rolls in mesh with the internal gear annuli of the hinge members, as a result of which there comes into existence a relative movement between the hinge members. These relative movements can be utilized for the adjustment of the position or inclination of a backrest component of a seat.
These conventional arrangements, as advantageous as they may be in some respects, are also possessed of some disadvantages. One of these disadvantages resides in the fact that the gears which function as adjusting members mesh with the internal gear annuli only at one zone of their circumference so that the gear teeth have to have relatively huge dimensions to be capable of sustaining the high forces acting thereon, especially when the vehicle equipped with the seat having one of these inclination-adjusting arrangements is involved in a collision. In addition thereto, due to the play between the flanks of the teeth and the region of the bearings due to manufacturing tolerances, wear or the like, there comes into existence a relatively large radial play which can result, during the operation of the vehicle, in rattling of the unused seat.